Fabrication of silicon nanodots on insulator using block copolymer thin film

Dense and periodically distributed silicon nanodots were fabricated on silicon dioxide layer using block copolymer. Self-assembling resists were coated on the polysilicon/oxide/silicon substrate to produce a layer of uniformly distributed parallel nano-cylinders of polymethyl methacrylate (PMMA) in a polystyrene (PS) matrix. The PMMA cylinders were degraded and removed by acetic acid rinsing, forming a PS template to transfer the pattern. The patterned cylindrical vacant cavities of the PS template were approximately 22 nm in diameter, 40 nm deep, and 50 nm apart. 5-nm- and 6-nm-thick Ni thin films were deposited by using an e-beam evaporator. The PS template was removed by a lift-off process using N-formyldimethylamine (DMF). Arrays of Ni nanodots were dry-etched using fluorine-based reactive ion etching (RIE), forming silicon nanodots. The sizes of the silicon nanodots were in the range of 10 nm to 30 nm, depending on the etching time.